telling juveniles from females?

[potatoe-mouse]

Does anyone have any tips from telling Juvenile birds from females? I'm having trouble telling the difference with the House Sparrows (a bit chubby and stumpy and shaking her wings) and Green/Gold/Caffinches especially - unless they are begging for food of course! I have also seen a dull coloured Jay that was lanky with its crest sticking up and acting really gormless, but I really wasn't sure.

[htcdude]

With House Sparrow the juvenile has a pinky/yellow bill and more a brown/buff colour all over.

There are good books out there also to help with the different features for other birds, I have this book:

9781845333386: Bird: The Ultimate Illustrated Guide to the Birds of Britain and Europe | New, Second-hand, Rare | Alibris UK

which is brilliant (I think you can get it cheaper if you hunt around)

Nige

[beech]

First pic is of a female greenfinch and the second a young recently fledged greenfinch. The young greenies tend to slightly yellower, a tad smaller but always have the streaking on the front, Not the best of pics but they will do to show comparison

[Hedera]

Young sparrows' legs look more yellow than the parents.

[Dogghound]

Juvenile birds tend to be more washed out versions of the adult birds (often adult females) in regards to small passerines like finches and sparrows. Each species should really be approached differently, as they all vary in how they look and how similar they are to the adult. A clue can often be the gape flange in the corner of the mouth which can persist in some species after fledging.

House Sparrow Juveniles are a watered down version of the female, they tend to have more of a pale diffuse buff colouration to the upperparts with less sharp dark/black lines within the mantle and wing feathers. A mottled brown look to the crown and rump. They have a paler more yellow washed out bill often only just the tip in some birds (often with a gape for so long). They tend to be duller grey/buff on the underside. They also often show a more diffuse supercillium above the eye. It is sometimes possible to sex dark throated individuals which grow into males, or if a small white spot is present behind the eye. They then undergo a full post juvenile moult after about 5-6 weeks in which will last about 60-80 days after which they will be almost identical to the adult (non-breeding plumage) bird.

Finches are much easier IMO at this age. Goldfinch without going into any detail lacks the adults red face, so you end up with a brown faced drab looking goldfinch showing the dark wings (with white tipped feathers) and more washed out yellow bars (on primary coverts, buff on greater). Partial post juvenile moult then occurs in Aug-Sept, where becomes similar to the adult i.e. red face.

Greenfinch again relatively simple, they are heavily streaked brown and buff versions of the adults, upperparts and underparts streaked. With a base colour of buff/olive. They show the yellow edged primaries and alula giving a yellow wing panel when closed which is often less intense compared with the adult. Birds of this age can be sexed although not often in the field. They then undergo a partial post juvenile moult where they look more adult like apart from subtle differences i.e. wings.

Chaffinch can be subtle and do look very female like but tend to be much more washed out with a more plain buff head colour which lacks the sharpness of an adult female. They also show a much duller green rump than on females. As with the other species juveniles show much fresher less worn flight feathers incomparison with adults. Juvenile males often start to show grey on the nape and crown from quite a young age lower mantle and show a tawny edge to the scapulars whch is more brown-grey or olive in females.

It is a massive subject which you could go into far greater depth than this, especially when looking at 1st winters (after post juv. moult). It just depends how much detail you want to go into. I will leave the Jay unless you think that was a young bird too (fingers getting tired of typing ).

[potatoe-mouse]

Wow! Thanks guys for all your advice, just what I needed. Is there anything about birds you don't know?